Summary of Employee Stock Options Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013
Stock Based Compensation Activity [Line Items]
Balance as of September 30, 2012, Number of Optioned Shares	125,550
Exercised, Number of Optioned Shares	(32,150)
Balance as of September 30, 2013, Number of Optioned Shares	93,400
Exercisable as of September 30, 2013, Number of Optioned Shares	93,400
Balance as of September 30, 2012, Weighted Average Exercise Price	$ 18.91
Exercised, Weighted Average Exercise Price	$ 18.91
Balance as of September 30, 2013, Weighted Average Exercise Price	$ 18.91
Exercisable as of September 30, 2013, Weighted Average Exercise Price	$ 18.91
Balance as of September 30, 2013, Weighted Average Remaining Contractual Term in Years	5 years 2 months 1 day
Exercisable as of September 30, 2013, Weighted Average Remaining Contractual Term in Years	5 years 2 months 1 day
Balance as of September 30, 2013, Aggregate Intrinsic Value	$ 1,267
Exercisable as of September 30, 2013, Aggregate Intrinsic Value	$ 1,267